Muffler for the exhaust system of an automobile

ABSTRACT

A muffler for the exhaust gas system of an automobile has a housing provided with two end walls and a circumferential wall and at least one exhaust gas channel passing therethrough. The muffler assembly also has at least two pipes, which mostly define the exhaust gas channel, which are arranged successively in the flow direction, and whose ends project into the interior of the housing. A transverse wall is provided in the housing, this wall being connected to the circumferential wall on the inside, running transverse to the exhaust gas channel and having an opening passing therethrough, said wall comprising at least two flexible wall sections in the axial direction, each having one edge adjacent to the opening, the ends of the pipes each being held at their outer side by the edge of at least one wall section.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority, under 35 U.S.C. § 119, of German patent application DE 10 2005 036 676, filed Aug. 4, 2005; the prior application is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The invention lies in the automotive technology field and relates, particularly, to a muffler for the exhaust system of an automobile.

In a design that is frequently encountered, a housing comprising two end walls and a circumferential wall has at least one exhaust gas channel passing therethrough, the exhaust gas channel being formed by two pipes arranged successively in the axial direction, each passing through an end wall and being fixed thereon. The ends of the pipes penetrating into the interior of the housing are usually each fixed to a housing structure, usually to a transverse wall, each pipe end being allocated a separate wall. The inner pipe ends are connected to the transverse walls by welding for example. Since the pipes are in direct contact with the hot exhaust gas, they expand, for example in the initial phase of vehicle operation, more strongly than the housing that is cooled by the airflow. Since the pipes are fixed at the end walls on the one hand and at an internal housing structure on the other hand, a change in length of the pipes brings about a corresponding mechanical loading of the end walls or the housing structures holding the inner pipe ends. As a consequence, the end walls and housing structures can become overstressed. The connection points, for example, the welded seams between the pipes and the end walls are exposed to a large number of alternating loadings when viewed over their service life. In this case, there is the risk that the pipes will become loose from their anchoring, which can result in rattling noises during vehicle operation.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a muffler assembly for an automobile exhaust system which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type.

With the foregoing and other objects in view there is provided, in accordance with the invention, a muffler assembly for the exhaust gas system of an automobile. The novel assembly comprises:

a housing formed with two end walls and a circumferen-tial wall and having at least one exhaust gas channel passing therethrough

at least two pipes primarily defining the exhaust gas channel, the pipes being disposed successively of each other in a flow direction and having ends projecting into an interior of the housing;

a transverse wall disposed in the housing and connected to an inside of the circumferential wall, the transverse wall extending transversely to the exhaust gas channel and having a through opening formed therein;

the transverse wall being formed of at least two wall sections, the wall sections being flexible in an axial direction and each having an edge adjoining the opening; and

the ends of the pipes being held at an outer side by a respective the edge of at least one of the wall sections.

In other words, the objects of the invention are solved by providing a transverse wall in the housing, the wall being connected to the circumferential wall on the inside, running transverse to the exhaust gas channel and having an opening passing therethrough. The wall is formed of at least two wall sections that are flexible in the axial direction, each having one edge adjacent to the opening, wherein the ends of the pipes are each held at their outer side by the edge of at least one wall section. In this embodiment, as in conventional mufflers, a pipe is fixed on the one hand to an end wall and on the other hand to an internal housing structure so that it is held securely and free from rattling both axially and radially. When axial and radial or axial direction and radial direction are talked about here, this definition relates to the longitudinal extension of the exhaust gas channel or to the central longitudinal axis of the pipes defining the exhaust gas channel. Any lengthening or shortening of the pipes caused by temperature variation is now compensated by the flexible wall sections in the axial direction so that the inwardly projecting ends of the pipes can expand freely without welded seams or other connections between the pipes and housing walls or the housing itself being stressed thereby.

The axial mobility of a wall section is provided in particular by the fact that this is elastically deformable and can thus be bent out from the plane of the transverse wall. A flexible wall section can be formed, for example, by providing zones of weakening, that is areas of smaller sheet metal thickness, running approximately radially in the transverse wall, which act as film hinges. Preferably however, the wall sections are formed by slots which are separated from the remaining wall region at the transverse wall and which therefore extend approximately radially away from the flow-through opening in the direction of the circumferential wall. Such a wall section can therefore bend elastically in the axial direction to a certain extent and thereby compensate for a change in length of a pipe. In the radial direction however, a wall section nevertheless ensures that a pipe is securely retained.

A further preferred embodiment provides that a wall section comprises a region which extends away from its edge and projects from the plane of the transverse wall. This embodiment allows two pipe ends retained by the transverse wall to be disposed at a greater axial distance from one another. In addition, the elastic properties of a wall section can be influenced by a region of this type.

The strength of the connection between a wall section and a pipe end can be increased if the edge of a wall section is formed by an axially extending collar, whose radially inwardly pointing side is connected to the outer side of a pipe.

In order to prevent the axial alignment of a pipe changing in the event of a heat-induced variation in length, the wall sections allocated to a pipe end are distributed uniformly over the circumference of the pipe. In particular, a pipe end is fixed respectively to a pair of diametrically opposite wall sections. Force components acting on the pipe in the radial direction are mutually compensated by said embodiments.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a muffler for the exhaust system of an automobile, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a section taken through a muffler assembly according to the invention;

FIG. 2 is a perspective view of a transverse wall seen in the direction of the arrow II in FIG. 1;

FIG. 3 is a plan view onto the transverse wall in the direction of the arrow III in FIG. 2;

FIG. 4 is a perspective view of a transverse wall with pipes fixed thereon;

FIG. 5 is a longitudinal sectional view of the assembly illustrated in FIG. 4;

FIG. 6 is a perspective view showing a transverse wall with pipes fixed thereon, the two pipes being inserted one inside the other;

FIG. 7 is a longitudinal sectional view of the assembly illustrated in FIG. 6;

FIG. 8 is a plan view of a transverse wall viewed in the direction of the arrow VIII in FIG. 6;

FIG. 9 is a perspective view of a transverse wall with pipes fixed thereon, the transverse wall comprising two differently configured pairs of wall sections;

FIG. 10 is a longitudinal sectional view of the assembly illustrated in FIG. 9;

FIG. 11 is a plan view of the transverse wall in the direction of the arrow XI in FIG. 9;

FIG. 12 is a plan view onto the transverse wall viewed in the direction of the arrow XII in FIG. 11;

FIG. 13 is a perspective view of a transverse wall with pipes fixed thereon, with modified wall sections as compared with FIG. 9;

FIG. 14 is a longitudinal sectional view of the assembly illustrated in FIG. 13;

FIG. 15 is a perspective view of the transverse wall viewed in the direction of the arrow XV in FIG. 13; and

FIG. 16 is a plan view onto the transverse wall viewed in the direction of the arrow XVI in FIG. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown a muffler assembly, or a muffler for short, with a housing 1 formed of a circumferential wall 2 having a circular cylindrical cross section, for example, and two end walls 3, 4. The end walls 3, 4 are connected to the circumferential wall 2 by a crimping or beading 5. A welded connection is also feasible at this point. An opening 7 provided with an extrusion 6 is provided in the end walls 3, 4, for example, in a central position. The openings 7 are each penetrated by an exhaust gas pipe 8, 9. The exhaust gas pipes 8, 9 are fixed to the extrusion 6, for example, are welded-on. They are disposed successively in the axial direction and define an exhaust gas channel 16. The ends 10, 12 of the pipes 8, 9 projecting into the interior of the housing are fixed to a transverse wall 13. The outer edge 14 of the transverse wall 13 is bent in the axial direction 15 and abuts against the inner side of the circumferential wall 2. Optionally, the outer edge 14 can be fixed to the circumferential wall 2, for example, by spot welding. At a position corresponding to the openings 7, the transverse wall 13 is penetrated by an opening 17. Approximately radial slots 18 distributed uniformly over the circumference are inserted in the transverse wall 13, which slots end at a distance before the outer edge 14 on the one hand and open into the openings 17 on the other hand. The slots 18 separate wall sections 19, 20 from one another. The wall sections 19, 20 can be deflected in the axial direction 15 from the plane 21 of the transverse wall 13 by elastic deformation. One pipe end 10, 12 is respectively fixed to a pair of diametrically opposite wall sections 19 a, 19 b or 20 a, 20 b. The edge 31 of a wall section 19, 20 defining a circumferential region of the opening 17 is embodied as a collar 22 extending in the axial direction 15, which is connected to the outer side of a pipe 8, 9 possibly by welding. In this case, the collar 22 of a wall section 19, 20 projects in the direction of the respective outer end of the corresponding pipe 8, 9. An axial distance 23 is provided between the two pipes 8, 9 in the exemplary embodiment shown in FIG. 1. However, it is also feasible, as is shown further below, that the two pipes 8, 9 are inserted one inside the other.

If hot exhaust gas flows through a muffler, possibly of the type shown in FIG. 1, starting from the cold state in the direction of flow 24, the pipes 8, 9 expand in the axial direction 15. Since the end walls 3, 4 act as anchor points, the pipes 8, 9 are each lengthened inwards. Accordingly, the wall sections 19 a, 19 b retaining the pipe 9 in the flow direction 24 and the wall sections 20 a, 20 b retaining the pipe 8 in the direction opposite to the flow direction 24 are deflected from the plane 21 of the transverse wall 13. The variation in length of the pipes 8, 9 is therefore compensated by the flexible wall sections 19, 20. This prevents or at least significantly reduces any deformation of the housing or stressing of the joining seams.

FIGS. 6 to 8 show an exemplary embodiment where the pipes 8, 9 passing through the housing 1 (omitted in FIGS. 6 and 7 for reasons of simplicity) are inserted one inside the other. The end 10 of the pipe 9 passes through the opening 17 and projects from the side of the transverse wall 13 pointing in the flow direction 24 with an overhang 25. The radially expanded end 12 of the pipe 8 a is positioned on this overhang. In this case, it is feasible that the pipe ends 10, 12 abut closely against one another in the fashion of a sliding fit. However, it can also be advantageous to provide an annular gap 26 between the pipe ends 10, 12. This ensures that the two pipes 8 a, 9 can easily be displaced axially during the entire service life. The expanded end 12 of the pipe 8 a is welded onto the collar 22 of the wall sections 20 a, 20 b. The radius of curvature 27 of the collar 22 of said wall sections is matched to the outer radius of the expanded pipe end 12, and is therefore greater than the corresponding radius of curvature 28 of the wall sections 19 a, 19 b (see FIG. 8).

In the exemplary embodiment shown in FIGS. 9 to 12, two approximately diametrically opposite wall sections 20 a, 20 b project from the plane 21 of the transverse wall 13 with a region 29. A region 29 extends coaxially in each case to the exhaust gas channel 16 or to the central longitudinal axis 30 of the pipes 8 a, 9. The region 29 runs in a plane parallel to the plane 21 of the transverse wall 13 and goes over into a region 33 running in the plane of the transverse wall 13 with a shoulder 32 running approximately in the axial direction. As a result of said configuration of the wall sections 20 a, 20 b, the collar 22 borne by said sections is at a greater distance from the plane 21 of the transverse wall 13 than is the case with the wall sections 19 a, 19 b. As a result, the pipe 8 can be arranged at a correspondingly greater distance from the plane 21 or a greater axial distance 23 (FIG. 10) can be formed between the pipes 8, 9. In addition, the elastic properties of a wall section 20 a, 20 b vary compared with a wall section 19 a, 19 b which is arranged almost completely in the plane 21 of the transverse wall 13.

In the exemplary embodiment according to FIGS. 13 to 16, the ends 10, 12 of the pipes 8, 9 are inserted one inside the other, as has already been described above. Accordingly, the radius of curvature 27 of the inner edge of a wall section 20 a, 20 b is greater than the corresponding radius of curvature 28 of a wall section 19 a, 19 b. The wall sections 19 a, 19 b allocated to the pipe 9 have a region 29 a which projects from the plane 21 of the transverse wall 13 towards the direction of flow 24. This region also runs coaxially to the central longitudinal axis 30. It is substantially formed by two beads 35, 36, the radially outer bead 35 being convexly curved opposite to the direction of flow 24 and the adjacent radially inner bead 36 being convexly curved in the direction of flow 24. The region 29 a can also be described as an S-profile when seen in cross section as in FIG. 14. Its radially inner end section or the end section of the bead 36 forms the collar 22 which is connected to the outer side of the pipe 9. The configuration of the wall sections 19 a, 19 b under discussion can be appropriate if a pipe is made of a material having a relatively high thermal expansion. The region 29 a acts like a bellows and ensures a relatively high mobility of a wall section 19 a, 19 b in the axial direction 15. The region 29 a is also compressible in the radial direction to a certain extent so that no stresses can build up in the wall sections 19 a, 19 b when the diameter of the pipe 9 is increased.

The wall sections 20 a, 20 b are configured like the wall sections in the exemplary embodiment of FIG. 1 to FIG. 5. It is also feasible that all the wall sections have a region 29 or 29 a or are configured differently from one another in another manner adapted to specific circumstances. 

1. A muffler assembly for the exhaust gas system of an automobile, the assembly comprising: a housing formed with two end walls and a circumferential wall and having at least one exhaust gas channel passing therethrough at least two pipes primarily defining said exhaust gas channel, said pipes being disposed successively of each other in a flow direction and having ends projecting into an interior of said housing; a transverse wall disposed in said housing and connected to an inside of said circumferential wall, said transverse wall extending transversely to said exhaust gas channel and having a through opening formed therein; said transverse wall being formed of at least two wall sections, said wall sections being flexible in an axial direction and each having an edge adjoining said opening; and said ends of said pipes being held at an outer side by a respective said edge of at least one of said wall sections.
 2. The muffler according to claim 1, wherein one of said wall sections is separated from a remaining wall region of said transverse wall by slots extending outwardly away from said opening.
 3. The muffler according to claim 2, wherein at least one of said wall sections has a region extending away from said edge and projecting away from a plane of said transverse wall.
 4. The muffler according to claim 1, wherein said edge of a respective said wall section is formed by an axially extending collar having a radially inwardly pointing side connected to an outer surface of a respective said pipe.
 5. The muffler according to claim 1, wherein each of said pipe ends has a plurality of wall sections allocated thereto, and said wall sections are distributed uniformly over a pipe circumference.
 6. The muffler according to claim 5, wherein one pipe end is respectively fixed to one pair of diametrically opposite wall sections. 